NEW YORK 
Scott Hairston’s drive bounced off the big wall in left, maybe a foot below the lip. Instead of having to pick up his step in a dash for second, Hairston slowed his stride to a trot.

Clearly, the New York Mets cleanup hitter was savoring not only the fact that his three-run homer off Clayton Richard launched the New York Mets to a 9-0 victory over the Padres, but the fact that it was a homer at all. A year ago, it would not have been. Most other ballparks, yes, but not at Citi Field. And definitely not at, well, you know where else.

Indeed, only an hour before Saturday’s game, Hairston literally was shaking his head at the memory of a similar blast when he was with the Padres. The shot fairly screamed “walk-off” as it soared toward the wall in left-center at Petco Park.

“I hit it square, hit it with everything I had, hit it as good as I could hit a ball,” he said. “I’m watching it go out, thinking, “That’s it. Game over.’ ”

So why was the center fielder still running? Oh yeah. Petco.

“My heart dropped when he caught it,” said Hairston. “Oh, man, that was painful.”

Almost as painful to Hairston were all those runs the Padres had scored in an 11-5 romp over the Mets a few nights earlier, the kind of scoring outburst you almost cannot imagine the Padres having in their own oversized ballpark. Word got back to New York that the Padres finally are giving serious consideration to bringing in their own fences, just as the Mets did at Citi Field after last season.

“When I came here a couple times as a visitor with Padres, it was reminiscent of Petco,” said Hairston, referring to Citi Field’s opening season of 2009. “Obviously, it’s a lot better now with the walls brought in.”

Sandy Alderson concurs. Wholeheartedly.

As CEO of the Padres, remember, Alderson was in charge when they did bring in the fences at Petco Park. OK, fence, a small section of it. Originally measured at 411 feet, a stretch in right-center was shaved to 400 feet, and that’s still a poke for any power hitter.

Alderson, then, had heard it all before when he moved to New York and became general manager of the Mets in 2010. He got a daily earful of the squawking from within his own clubhouse, the groans from fans after Mets home runs died in visiting outfielders’ gloves. Fact is, given his experience in San Diego, Alderson had sharpened his own opinion about too-big ballparks.

“Baseball purists might think that 2-1 or 3-2 or 1-0 night in and night out is the best form of baseball entertainment, but most people don’t,” said Alderson. “Me, personally? If I had to watch a game that was 1-0 or 2-1 every night, I’d move to England.”